package com.map;

import com.set.FileOperation;

import java.util.ArrayList;

/**
 * 使用二分搜索树来实现映射 map
 * @param <K>
 * @param <V>
 */
public class BSTMap<K extends Comparable<K>, V> implements Map<K, V> {

    /**
     * 原先自己实现的 BST 挂载的节点只能存一个数据，现在要自定义改
     * 成支持2个数的， k, v
     */
    private class Node {
        public K key;
        public V value;
        public Node left;
        public Node right;

        public Node(K key, V value) {
            this.key = key;
            this.value = value;
            left = null;
            right = null;
        }
    }
    private Node root;
    private int size;


    @Override
    public void add(K key, V value) {
        root = add(root, key, value);
    }

    /**
     * 使用递归算法向以node 为根的二分搜索树中添加元素，
     * 插入新节点之后返回二分搜索树的根
     * @param node
     * @param key
     * @param value
     * @return
     */
    private Node add(Node node, K key, V value) {
        // 递归到底就创建新的节点
        if (node == null) {
            size ++;
            return new Node(key, value);
        }
        if (key.compareTo(node.key) < 0) {
            node.left = add(node.left, key, value);
        }else if (key.compareTo(node.key) > 0) {
            node.right = add(node.right, key, value);
        }else {
            // 如果是原来的key, 那变成更新
            node.value = value;
        }
        return node;
    }

    @Override
    public V remove(K key) {
        Node node = getNode(root, key);
        if (node != null) {
            root = remove(root, key);
            return root.value;
        }
        return null;
    }

    /**
     * 使用递归删除以node 为根节点的二分搜索树中的节点
     * 返回删除节点之后新的二分搜索树的根
     * @param node
     * @param key
     * @return
     */
    private Node remove(Node node, K key) {
        if (node == null) {
            return null;
        }
        if (key.compareTo(node.key) < 0) {
            node.left = remove(node.left,key);
            return node;
        }else if (key.compareTo(node.key) > 0) {
            node.right = remove(node.right, key);
            return node;
        }else {
            // 待删除左子树为空的情况
            if (node.left == null) {
                Node rightNode = node.right;
                node.right = null;
                size --;
                return rightNode;
            }
            // 待删除右子树为空的情况
            if (node.right == null) {
                Node leftNode = node.left;
                node.left = null;
                size --;
                return leftNode;
            }
            // 待删除左右子树均不为空的情况
            Node successor = minimum(node.right);
            successor.right = removeMin(node.right);
            successor.left = node.left;
            node.right = null;
            node.left = null;
            return successor;
        }

    }

    /**
     * 返回以node为根的二分搜索树的最小值所在的节点
     * @param node
     * @return
     */
    private Node minimum(Node node) {
        if (node.left == null) {
            return node;
        }
        return minimum(node.left);
    }

    /**
     * 删除以node为根的二分搜索树中最小的节点
     * 返回删除节点后的二分搜索树的根
     * @param node
     * @return
     */
    private Node removeMin(Node node) {
        if (node.left == null) {
            Node rightNode = node.right;
            node.right = null;
            size --;
            return rightNode;
        }
        node.left = removeMin(node.left);
        return node;
    }

    @Override
    public boolean contains(K key) {
        return getNode(root, key) != null;
    }

    @Override
    public V get(K key) {
        Node node = getNode(root, key);
        return node == null ? null: node.value;
    }

    @Override
    public void set(K key, V newValue) {
        Node node = getNode(root, key);
        if (node == null) {
            throw new IllegalArgumentException(key + "doesn't exist!");
        }else {
            node.value = newValue;
        }

    }

    @Override
    public int getSize() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        return size == 0;
    }

    /**
     * 返回以node为根节点的二分搜索树中的key所在的节点
     * @param node
     * @param key
     * @return
     */
    private Node getNode(Node node, K key) {
        if (node == null) {
            return null;
        }
        if (key.compareTo(node.key) == 0) {
            return node;
        }else if (key.compareTo(node.key) < 0) {
            return getNode(node.left, key);
        }else {
            return getNode(node.right, key);
        }
    }

    public static void main(String[] args) {
        String filePath = "E:\\WorkSpace\\LearningDemoWorkSpace\\data-structure\\src\\pride-and-prejudice.txt";
        ArrayList<String> words = new ArrayList<>();
        if (FileOperation.readFile(filePath, words)) {
            System.out.println("Total words: " + words.size());
            BSTMap<String, Integer> map = new BSTMap<>();
            for (String word: words) {
                if (map.contains(word)) {
                    map.set(word, map.get(word) + 1);
                } else {
                    map.add(word, 1);
                }
            }
            System.out.println("Total different words: " + map.size);
            System.out.println("Frequency of pride: " + map.get("pride"));
        }
    }




}
